Morphology Dependence of Silicon Nanowire/Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) Heterojunction Solar Cells

The characteristics of well-aligned silicon nanowire (SiNW)/poly(3,4-ethylenedioxy- thiophene):poly(styrenesulfonate) (PEDOT) heterojunction solar cells with varying nanowire lengths are investigated. PEDOT adheres on the hydrophilic n-type silicon nanowire surface to form a core−sheath heterojunction structure through the solution process. Such a structure increases the area of heterojunctions and shortens the carrier diffusion distance, and therefore, it greatly increases carrier collection efficiency. The cells exhibit stable rectifying diode behavior. Compared to the cells without a nanowire structure, the series resistance of the SiNW/PEDOT cell decreases from 60.42 Ω cm2 to 1.47 Ω cm2, and the power conversion efficiency improves from 0.08% to 5.09%. The SiNW/PEDOT solar cell harvests photons from 400 nm to 1100 nm and a maximum incident phototo-current conversion efficiency of ∼32% at 700 nm.